The present invention relates generally to closure devices with interlocking fastening strips and, more particularly, to reducing curvature in interlocking fastening strips. The invention may be employed in traditional fastener areas and is particularly well suited for use in manufacturing closure devices for flexible storage containers, such as plastic bags.
The use of closure devices for closing storage containers, including plastic bags, is generally known. The closure device and the associated container are formed from thermoplastic materials. The closure elements are extruded onto a flange portion and in a later step, the flange portion is attached to the sidewalls of the container. This method may cause the flange portion to curve upward along the horizontal axis as shown in FIG. 4.
The present invention reduces the curvature of the flange portions in the horizontal axis which occurs during the manufacturing process. The closure device includes closure elements extruded onto a flange portion. By altering the densities of the closure elements and the flange portions, the flange portions will have less curvature in the horizontal axis.
The objects, features, and advantages of the present invention will become more readily apparent upon reading the following detailed description of exemplified embodiments and upon reference to the accompanying drawings herein.